Telephone automatic trunking apparatus



' Jan. 30, 923. 1.443,494

T. G. MARTIN. TELEPHONE AUTOMATIC TRUNKING APPARTUS.

ORIGINAL FILED JAN. I7, 1907. 4 sI-II-:FIs-sHI-:ET l

II I. I

Jan. 30, 1923.

T. G.MART 1N. TELEPHONE AUTOMATIC TRUNK Ne APPARATUS.

4 sHEET$-sHEET 2 ORlG NAI. F| LED JAN. 17. 1907,

4 www 'T. G. MARTIN. TELEPHONE AUTOMATIC TRUNK Nc; APPARATUS.

4 SHEETS-SHEET 3 0R G l NAL Fl LED JAN. I7 1907.

T. G. MARTIN TELEPHONE AUTOMATIC TRUNKING APPARATUS.

ORIGINAL FILED JAN. I7, 1907. 4 SHEETS-SHEET 4 503171472 @A5/54951 65.2%f ff I W Patented Jan. 39.19.23;

UNITEII TA'I'ES Parent TALBOT o. MARTIN, or CHICAGO, ILLINOIS, assIsNon,'er IansNnAssIGNivinNrs, To `AU'roivIATIcnnncfrnrcCOMPANY, AconroeafrIoN or ILLINOIS.

TELEPHONE AUTOMATIC TRUNKING APPARATUS.

yApplication led January 17, 1907, SerialfNo. 352,894. Renewed.Tanuary'28, 1918. Serial No; 214,252.

` To @Hamam/ may concern.' K

Be it known'that I, TaLnorG. I/LIRTIN, a citizen ot the United States ofAmerica, and resident of Chicago,`Cool C n1i1ity,Illi `5 nois, haveinvented a certain new and useiu'l Improvement yin Telephone uton'iatic'Ilrunking Apparxrtumot which the tollowing' is aspecitication.

My invention relates to Atelephone er-I change systems in general, butmore particularly to automatic `or semi-automatic sysw tems, andespeciallyto` common battery tele- `phone .exchange systems in whichprovision is made for enabling` the'calling subscribers to automaticallytrunk betweentwo distant exchanges, or between different divisions oithe same exchange.

.Inmy Patent No. 1,185,522, granted May 30, 1916, I have disclosed acombined selec- L torand repeater,vandias tar as'this yfeature ot my`present invention is concernethit is in the nature of an improvement onsaid `previous application. As 'hereinafter described, 'I now provide yacombined selector and repeater-which vis adaptedfor use in trunking inone and the same directionthat is to say, which has the 'functions ot'both a selector and arepeater torftrunlring to another exchange,or totheother division ofthe same exchange. A herein disclosedv embodimentofmy present invention com-k prises, for example, a first-selector whichis individual to the calling subscribers line, which is provided withmeans tor automatically selecting an `idle trunk line, and which isfurther provided with means 'by which its line relays have theadditional function of: then acting as repeater relays tor`controllingone or more automatic switches at the other exchange. or atthe other division ot the same exchange. ln another embodiment ot' myinvention, as herein described and illustrated, I provide`seconthselectorswith which Vthe calling sub-- seribers make connectionthrough the medium of first-selectorsor 'other suitable automaticswitches, and which second-selectors are adaptedto serve as bothselectors and repeaters for automatically trun'lring vto and `thenvcontrolling the operations ot the switches at the Aother exchange. orat. the other `division of the same exchange. In these/as wellvas inother obvious embodiment-s of my invention, it will "be seen that Iprovide `a system and apparatus ot 'such character rthat the callingsubsc 'iber may 7 tiene@ transmit electrical impulses foroperatinp;

an automatic selector switch containing means by whichk all subsequentimpulses transmitted 'from the callingv substation are not employed I'ordirectly controlling -the switch ror switches at the other exchange, orat the other division ol` the same exchange, but to the contrary `areemployed for merely actuating a pair ot linerelays which repeat theimpulses and thus directly control the operations of vthe next orsucceeding-switch or switches. In other words, I provide an automatic`trunk-selectingswitch having a pair of line relays adapted to firstcontrol the operations ot' the said switch, and, atter'theproperselection thereby of an idle trunk line, then repeat to the y next orsucceeding ,switch or switches yall subsequent electrical impulsestransmitted byv 'the calling` subscriber. y'In thisway the said linerelays have Athe double function controllingtheir allotted switchmechanism and servingas repeater relays for controlling` other automaticswitches. rFurthermore, andas a `feature of special improve ment, these`relays not only lhave the double function of .controlling their allottedselectors and repeating impulses to the subse quentswitoh or switches,but also have the additional function otserving as resistance andimpedance elements for feeding ,talks ing current from the battery orother cen` tralized source to the calling subscribers line fortalking'.purposes-that is to say, `for charging theimicrophonetransmitter at the 'fallmg subscribers substation.` Vith these andsuchother 'features and 'Combinations as may appear from Vthe following,-description and accompanyingdrawings,- I Iind.v that a. considerablesaving' is accomplished. especially with respect to the kcost 0I' in-vvstallingi and maintaining;` the apparatus` well as with respect to theprimarycost ot (.-onstruction or manufacture. I

` In the accompanying drawings, Yl `igares 't and 2 'taken together showdiagrammatically an established connection between a calling and acalled substation, in a system f embodying the `principles of my"invention, The telling substation is shown at and the calledsubstationat A. vFor-thebroader purposes of my invention,` 'thesubscribers may `be considered. allotted to either the.

, same or different exchanges; butin `this'mise iolv ` .by manywell-known features. For example: The subscribers lino vor `individualswitch C is an improvement on the selector shown in Patent No. 815,321..grunted March 13, 1906,to Keith, Erickson and lhfickson. The said switch(l, in additionto performing` the ordina-rv functions ot the selector,also performs the functions oil a repeater, as will be explained. Thus lcombine in one switch the features ot a selector and a repeater for usein trunking or calling in one and the same direction. f

The selector F is a modified form of selector, being used in the systemasa secondselector; and the connector D is an improvement on theconnector shown in Patent No. 815,176, granted March'18, 1906, to Keith,Erickson and Erickson, being an adaptation or' such connector for commonbattery work. The switch E of the called line-is, ot course, the same'as' the switch C ol the calling line; and the substations are also, oicourse, all the same; but where only one battery is used for two or moreexchanges aV battery lead must ot necessity be extended from the batteryoffice to the other central oiiices. This, however, isusuallyundesirable in most cases, and one battery is therefore provided foretiche-Xchange, as shown in the drawings, where battery B is allotted toeXchanget1 and grounded at G, and where battery B is allotted toexchange and grounded at G.

Fig. 3 of the d rawings shows the switch C used in a different positionin the system-- that is, after the selector .l-and is therefore used asa second-selector. The said selector J is also of the type-disclosed iuthe.y

said selector patent.

Fig. 4 shows the switch C diagran'unatically and in perspective.

The substations A and A may be of any suitable or approved type. A-comprisesl a receiver 2, switch-hook 3, in-

duction-coil 4 which consists of the primary winding 5 and secondarywinding 6,v transmit-ter 7, condenser 8, ringer 9, impulse wheel 410which has the usual vertical impulse teeth 11 that are adapted tooperate the vertical impulse spring 12. The impulse wheel carries 'therotary impulse tooth 13 The substation which operates the rotary impulsespring 14. The switch-hook has radiating from its body a number of camarms 15, 16 and 17, and is pivotally secured to the keyboard (not shown)by the screw 1S about which it moves when the receiver is removed.V Themovement is produced by a spring (not shown), and the switch-hook ispushed up for the purpose ot changing certain circuit connectionsto bedisclosed. The cam arm 15 controls the so-called locking arm 19. Afterthe dial is rotated the locking arm 19 occupiesthe position shown atsubstation A. rlhe mechanical operations by which this brought about arewell known. vrllhe' cooperating groiind springs 2t) and 21 engage, thusplacing the groundpost in contactwith the substation ground ti. wherebywhen the subscriber releases the dial, as dcs'cribed, the verticalimpulseteeth 11 will then cause the vertical. impulse spring 12 to' comeinto Contact with the ground post 22; and immediately following, therotary 'impulse toothvr 13 causes the rotary impulse spring' 14 toco-meinto contact with the same ground post 22. When the switch-hook is downthe cam arm 17 maintainsa contact between the springs and 24, therebybridging the condenserl 8 in series with the ringer 9 across the line.The springs 25 and 26 are then disengaged, and thel primary circuit,including the winding 5' in series with the transmitter 7, isinterrupted by the separation of the springs 25 and 26.' The signalingdevice whereby a subscriber may' signal another after a connection hasbeen established comprises a push-button 28 and a spring 29, whichlatter normally engages the contact point 30; but whenthe push-button-28is pressed, the spring 29 leaves the contact point 30`and engages theContact point 31 which is connected with the substation ground G. Meanswhereby the subscriber may release the central station apparatus broughtinto service comprises three springs 32, 33' and 34 known as the releasesprings, and so controlled bythe cani arm. 1G that when the switch-hookdescends thc three release springs are brought'into con.- tact, therebygrounding both the subscribers line conductors simultaneously.

.lhetirst-selector switch C, shown in Figs. l, 3 and 4, embodies, amongother details. the vfollowing 'well known devices and circuits: Aswitch-shaftJ 38 which carries the vertical and rotary line wipers 39and 40, respectively, and. the private wiper 41. The said wipers areadapted toengage the banks K and L. The side switch M is well known andcomprises the side switch wipers 42, 43, 44, 45 and 35 whichmay bedesignated vertical, rotary and private f side switch wipers, and therotary magnet side switch wiper and pole-changer wiper, respectively.rlhe side switch is under the controlo? the llt Mii

. ent is omitted in the selector' F. cal line relay 64 controls thevertical magprivate magnet 46. Through the medium of the vertical linerelay 47, and while the side switch is in iirst position,the'subscrbercontrols the vertical magnet 48 which latter operatestoraise the shaft and shait wipers 39,4() and 4lrvertically. By means ofthe rotary line relay 49, and while the side switch is in vtirst vorseco-nd position, the subscriber controls the private magnet 46 and,therefore,.the side switch. While the side switch is in second positionthe rotary magnet 50, which carries the shaft and shaft wipers `in arotary or circular direction, is energized. The vertical and rotary linerelays 47 and 49, acting conjointly, vprovide means whereby thesubscriber controls the release magnet 5l while the side switch is inFirst, second or third, position.` The polechanging relay 3G is providedfor shifting the lead of the'rotary line relay 49 from main battery tothe ground terminal of the battery when talking battery current isprovided bythe connector. Ilurthermore, the shaft 38 is provided withthe vertical and longitudinal teeth 52 and 53, respectively, which areadapted to be engaged by the rotary and vertical armature pawls 54 and55 when their respective magnets become operatively energized-- Thenormal arm 56 controls the springs 57 and 58, The function of the coilspring 59 is to return the sha'tt 38 to normal position after the saidsha'tt has been released by the operation ot the release magnet 51. Thelamp 60 is provided tor indicating tothe switch attendant whether or notthe switch isin an operated position. It will be noticed that through`the condenser 6l the subscribers incoming verticalline conductor istransposed to the outgoing rotary line; similarly, through the condenser62 the subscribers incoming rotary line conductor is transposed to theoutgoing vertical line` The differed tial relay 63 controlsthe releasemagnet circuit, and when the side switch M is in third position the saidrelay controls the energizing circuit ot the pole-changerrelay 36.

The Lsecond-selector F has the vertical and rotary line relays G4 and65, but insteadot being connected to the battery lead through theln'idge-cut-ot springs, said relays are connected direct to the batterylead. The ln'idge-cut-oit relay of the said selector patrihe vertinet(36, and the rotary line relay 65`controvls the private magnet G7, whichlatter in turn controls the side switch. The two line relays 64 and 65,acting conjointly, provide means whereby the release magnet 68 maybecome energized. The release relay 69 controls the releasing ot theswitch after the side switch has passed to third position andestablished connection with a connector switch. li'luthcrmore, therotarymagnet 7 O,

when the side switch is in second position,

operates to give the shaft wipers 7l, 72 and 7 3 a rotary or circularmotion. i

The connector l) is ot the type disclosed in my latent No. 1,382,226,granted `March `2, 1920. The vertical and rotary `line relays 74 and 75operate to impart to the shaft wipers 7G, 77and 78 their vertical androtary motion, respectively-` While the side switch is in rst position,the vertical line relay 7 4 controls the vertical magnet 7 9, and when'the side switch passes to second position the rotary magnet comesunderthe control` ci the said relay; and similarly, when the side switch isin third position the ringer relay 8l is placed underfthe ycontrol otthe vertical line relay 7 4. The connector rotary linerelay 75, as iswell known, controls the private magnet 82, which'latter in turnoperatesto shift the side switch wipers 83, S4, and 86 'trom iirst tosecond po-VK sition and from second to third position. The two linerelays 74 and 75, acting conjointly, provide means whereby the releasemagnet 87 may be energized to relea'sethe said switch. rThe`diiierential relay 88 controls the energizing circuit of thelbackbridge relay S9, throughwhich Vlat-ter the called substationrecevies battery current for talking purposes. Said relay 89,uponenergizing, closes a circuit which in turn pro vides the callingsubstation with battery los the switch-hook 3 and operating the dialfor.

, the iirst digit 2, the vertical and rotary line conductors 90 and 91are alternately ground ed, the formed ytwice and the latter once,V

upon the return motion ofthe dial. Grounding the vertical line conductor9() closes an energizing circuit through the vertical line relay 47 otthe lselector (l, said circuit `temling from.ground Gf through theground springs 2() and 2l, ground post 22' impulse spring l2, conductorSii/),conducto'r 92, vertical line relay 47, windingflotthediti'erential relay to the battery lead 94, thence through batteryB and to ground Gr.` Each time that the 'vertical line relay47 operates,

iis

an energizing circuit is established.through the vertical magnetextending froml ground G2 through the springs 95 and 9G, conductor l7,-side switch wiper 42,A contact point 9S, through the vertical magnet48,

fil (l conductor 99, private magnet. springs v100 and 101, conductor102, springs 103 and 104 to the battery lead 94. thence throughbattery Band to ground G. The vertical magnet 46 `in turn operates to raise theshaft and s-hattwipers 39, and 41 two steps. Following 4the verticalimpulse the rotary line relay 49 becoi'nes energized over a cir,- cuitextending from ground G, impulse spring 14, rotary line conductor 91,conductor 105, rotary line relay 49, winding 106` Vofthe diiizerentialrelay 623, through the springs 103 and 104 to the battery lead 94,ltllence through battery B and to ground G. The rotary line relay 49,upon operating, presses the springs 95 and 10T into contact, wliereby auenergizing circuit is closed through the private magnet '46 eX- tcndingfrom groundjGz, springs 95 and 107, conductor 106, side switch wiper 43,contact point 109, conductor 110. pr- 7ate magnet 46 lto the batterylead 94, thence through battery B and to grounc G. The private inagnet,upon o 3er-ating, releases the side switch M to second position, wviereby an energizing circuit isset up through the rotary magnet 50.Said circuit extends trom ground G3 lthrough the side switch wiper 45,contact point- 1'11, conductor 112, interrupter springs 113', rotarymagnet 50 to the battery lead 94, thence through battery B and to groundG. The rotary magnet is energized one step, and the shaft wipers 39, 40and 41 are carried into engagement with bank contacts that constitutethe terminals of a trunk line the conductors ot which are similar to thetrunk conductors 113 and 114 leading from the tenth set ot contacts ofthe second level, and which conductors 113 and 114 terminate in theswitch F at the exchange #2. But it the i'irst trunk line is busy theiirst private bank contact is, of course, grounded, and an energizingcircuit is established through the private magnet 46 when the L rivatewiper 41 strikes the grounded private ybank contact, thereby retainingthe side switch in second position and maintaining the energizingcircuit through the rotary magnet 50. The rotary magnet, by continuingto rotate the wipers, breaks the energizing circuit ot the privatemagnet 46 as soon as an idle trunk line is found, and as soon as theprivate magnet de-energied the side switch is 'tripped into thirdposition; but if there are no busy contacts to be passed over, therotary magnet 50, as is'well known, trips the side switch to thirdposition. It', iowever, the iirst nine trunks are busy the shaft will' berotated onto the tenth set ot side switch wipers 42, 43, 44, and engagetheir respective contact points 115, 116,

11'?, 113 and 119, thus extending the subscribens line conductors and 91to the se-l lector F. Also, since the side vswitch wiper 44 engages thegrounded contact point 11T, a guarding potential is established at theprivate wiper 41 tor protecting the seized trunk line trom beingmolested by any other switch. Furthermore, on the iirst vertical step'of the shaft the normal arm 56 permits the normal springs 57 and 58 toengage. thereby closing a circuit through the signal lamp 60 as follows:from ground G1 through the springs 57 and 5S, lamp 60 to the batterylead 94, thence through battery B and to ground G. The lamp, uponglowing, indicates to the switch attendant. that the allotted switch isin anv operated position. The subscriber, upon grounding the lineconductors 90 and 91 tor the second digit 2, energir/.es the verticaland rotary line relays 4T and 49 as before, since the line rel ys arepermanently bridged acrossthe line; but. the said relays upon energizingin turn operate to ground the trunk conductors 113 and 114, as will beexplained. Now, since the side switch v4 has passed to thirdl iosition,the impulses are repeated to the vertical and rotary line relays 64 and65, respectively, ot' the selector switch F which is located in thecentral office .71722. The vertical line relay 4T energizes and operatesas stated; but when the springs and 96 engage, an energizing circuit isclosed through the vertical line relay 64 at the selector F over theitollowing circuit: From ground G2, springs 95 and 96, conductor 97.wiper 42, contact point` 115, conductor 120, springs 121 and 122,conductor 123, shaft wiper 39, trunk conductor 113, side switch wiper124, contact point 125, vertical line relay 64 to the battery lead 126,thence through battery B and to ground G. The vertical line relay 64upon energizing places the springs 127 and 128 in contact, therebyclosing an energizing circuit through the vertical magnet 66 extendingtrom ground G5 through the springs 12T and 123, private springs 129 and130, vertical magnet 66, 'thence to battery lead 126, and 'from batteryto ground G. rhe vertical magnet v,operates to carry the shalt wipersT1, 'i' 2 and 73 two steps opposite the bank level in which are locatedthe terminals ot the trunk lines leading to' the connectorD, Fig. Therotary line relay 49 of the selector C upon energizing places thesprings107 and 95 in contact, .,Vhereby an energizing `circuit is closedthroughthe rotary line reiay 65 ot the selector switch F. This circuitextends from ground G2 through the springs 95 and y107, conductor 108,side switch wiper 43,

contact point 116, conduct-or 131, springs 132 and 133, conductor `134,shaft wiper 40, rotary trunk conductor 114, side switch wiper 135,contact point 136, rotary line relay 65 to 'the battery lead 126, thencethrough battery Bto ground G. The rotary line relay 65, upon energizing,closes an energizing whereby an energizing circuit is closed through therotar" magnet extendinol o M t x 2,-; trom ground (J, Contact point 108,side switch wi'ier 139 interruater sorinos 14() through the rotarymagnet mito the battery leady '126, thence through battery B to groundG. The rotary magnet, upon'operating, rotates the shaft wipers, as iswell known, onto an idle trunk line. 'Vhen the idle trunk line is seizedthe side switchV wipers pass to third position, thus extending thecalling' subscribers line conductors 90 and.` 91 to the conductors 141and 142 which, it will be assumed, lead to the connector D.Furthern'loro, when the side switch wiper 143 passes to third position,a guarding potontial is established at the private wiper 7K1 (whichlatter has engaged the conductor I4/1 rlor. protecting the seizedy lineagainst being molested byother switches. The et'- t'ect out groundingthe line conductors 90 and 91 for the last two digits (naught andnaught) is directed toward the connector D bjr' the selector switch C inthe manner in which the second digit operation was directed toward theselector switch F. Grounding the verticalline conductor 99 'ten timesfor the third digit operates the vertical line relay 47 ot the selectorswitch C ten times, aspreviously explained; the said relay inturnrepeats the ten impulses, grounding the vertical trunk` line conductor113 ten times, which conductor is now extended to the connectorverticalline relay 74. The connector vertical line relay 74, therefore,becon'iesenergized over a circuit extending from ground G2 at theselector C, as explained, to the conductor 113, thence through the sideswitch wiper 124, contact point 145, conductor 141, vertical line relay74,through the winding 146 ot the ditlerential relay 8S to the batterylead 126, thence through battery 13A to ground G. rThe relay 88, of

course, becomes energized, since the winding .146 is in series with thelrelay 74; but the energization o't the said'diliercntial relay at thistime is without effect.

Each; time that the vertical line relay 74 is energized the line relaysprings 147 and 148 are pressed` into contact, thereby closing anenergizing circuit` through the vertical magnet 79 over the followingpath: From ground G tothe springs 147 and 148-, private magnet springsl149 and 150, side switch wiper S6, Contact point 151, vertical magnet79 to the battery lead 126, thence throngh battery B to ground G. Thevertical mag`- niet, thus energized, operates to raise they shaft andshaft wipers one step at a time until the said wipers arecarried tensteps 1 to the bank level in which are-located the terminals ot the lineal1-2200. lVhen the rotary line conductor 91 is grounded the r0- taryline relay of the switch@ is energized, which in turn operates to groundthe rotary trunk conductor 114, whereby the connector rotary line relaybecomes energized through the following path :from ground G2 to therotary trunk line conductor 114, as eplained, side switch wiper 135,contact point 152, shaft wiper 72, trunk conductor `142, rotary linerelay75, winding 153 of the differential relay 8S, springs 154 and 155to thebattery lead 12G,`thence through battery B to ground G. Since thewinding'153` ot the differential relay 88 is in series with the rotaryline relayl 75, the difterential relay 88 becomes operative, but' atthis time `it is without effect. The energiza.- tion of the rotary linerelay 7 5 causes the energizationy of the private niagnet 82 over acircuit extending 'trom ground G through the springs 147 and 156 to theprivate magnet 82, springs 154 and 155 to the battery lead y126, 'thencethrough battery B t()` ground G. released from first to second position,thus placing the wipers 83, 84, 85 and 86 ink connection with thecontact points of Lthe second position. The last digit beingnaught, thesubscriber operates the dial, as previously described7 grounding thevertical `linelconductor ten `times and the rotarylineconductor 91 once.The vertical and rotaryline relays 74 and 75 are opera-ted over`previously traced circuits. However, when the connector line relaysprings 147 and 148engage, a circuit is closed throughthe rotary magnet8O instead of through the verticali As a result the side switch is`magnet 79. `The energizing circuitextends from ground G through thesprings 147 and 148, private magnet springs 149 and 15,0, side switchwiperSG, contact point 157, `rotary magnet S9` to the battery.` lead126,thence through battery B to ground G. time that the rotary magnet isenergized it operates to rotate theshatt and shaft wipers 7G, 77 and 78one step at time until the Each said wipers are carried into engagementwith the normal conductors 159, 159 and 1GO. the 'toriner two ot whichload to the line ,terminals of the desired: subscriber. V

operation is brought about inthe welk" lsnown` manner.v Assume theformer result to occur and the side, switch to pass to' third position,tlnis'placm'g-the side switch wipers 83, 84, 85 and 86 in contact withtheir i ispective fontact points in third position. Furthermore, whenthe side switch passes to third'position a guarding potential. isestablished for protecting the called line. This potential extends fromground G7, contact point 161 to the side switch wiper 85, switch shaftwiper 78, which latter engages the private contact of the called line.The said guarding potential also closes an energizing circuit throughthe pole-changing and cutoff relay '162 of the selector E. To signal thecalled subscriber the calling subscriber presses the signaling button28, placing the contact 29 in contact with the substation ground,thereby energizing the selector vertical line relay 47 and in turn theconnector vertical line relay 74. The path of the energizing circuitextends from ground Gr through the springs 2O and 21, contact point 31,spring 29, springs 26 and 25 to the vertical line conductor 90, thusenergizing the selector vertical line relay 47, as explained. r1`he saidrelay repeats the impulse from ground G2 to the conductor 113, sideswitch wiper 124, contact point 145, shaft wiper 71, conductor 141,through the vertical line relay 74, winding 146 of the differentialrelay 88 to the battery lead 126, thence through battery B and to groundG. It will be remembered that the connector side switch has passed fromsecond to third. position, and that the side switch wiper 86 is inengagement with the contact point 168, thereby placing the vertical linerelay 74 in control of the ringer relay 81 in the same manner in whichthe rotary magnet 8O came under the control of the vertical line relaywhen the side switch passed from first to second position. Therefore,when the vertical line relay presses the springs 147 and 148 intoContact. the ringer relay 81 is energized by a low of current fromground G through the springs 147 and 148, private magnet springs 149 andl150, side switch wiper 86, contact point 163, ringer relay 81, springs164 and 165 (bearing in mind that the differential relay 88 isenergized) to the battery lead 126. thence through battery B to `groundG. The ringer relay, upon energizing. shifts the spring 166 out ofcontact with the spring 167 and into engagement with the spring 168.`and the spring 169 is shifted into engagement with the spring 170. This`results in bridging the terminals of the ringer vgenerator lil acrossthe called subscribers line'. A signaling current is therefore sent fromthe generator H to the ringer relay springs 170 and 169, side switchwiper 88, contact point 171, shaft wiper 7 6,

normal conductor 158, vertical line conducA tor 172, condenser 173,ringer 174, springs 1.7 5 and 176 to the rotary line conductor 17 7,rotary normal conductor 159, shaft wiper 77. cotnact point 178, siedswitch wiper 84,

ringer relay springs 166 and 168 back to the generator H. As soon as thecalling subscriber ceases to press the signaling button 28 the ringerrelay 81 becomes de-energized and the springs 166 and 169 resume theirnormal positions. The subscriber at substation #2200, in response to thesignal, removes the receiver 179 from the switch-hook 180, which allowsthe springs 181 and 182 to engage, and the springs 175 and 176 todisengage, thereby removing the ringer 174 from across his line. Theengagement of the springs 181 and 182 closes a series energizing circuitthrough both windings of the relay 89 at the connector D, said circuitextending from ground G7 to the contact point 161, side switch wiper 85,winding 1.81 of the relay 89, through the ringer springs 167 and 166,side switch wiper 84, contactk point 178, shaft wiper 77, rotary normalconductor 159, rotary line conductor 177, primary winding 182,transmitter 188, through the signaling device of the called substation,through the springs 181 and 182', vertical line conductor 172,'normalconductor 158. shaft wiper 76, contact point 171, wiper 83, through thewinding 184 of the relay89, springs 185 and 165 to the bat tery lead126. thence through battery B and to ground G. The relay 89, uponenergizing, operates to shift the spring 154 from the spring 155 (whichlatter is connected to the battery lead 126) to the spring 186, which isin turn connected with ground. This reversal of the polarity of thespring 154 sets up a circuit which energizes the pole-changing relay 36of the selector C. Thiscircuit may be traced from ground G7 to thecontact point 161. side switch wiper 85, through the springs 186 and154, winding 158 of the differential relay 88, rotary line relay 7 5,conductor 142, shaft wiper 72, side switch wiper 135, rotary trunk lineconductor 114. shaft wiper 40, conductor 184 (Fig. 4). sin-.ings 186 and187, contact point 119, side switch wiper 85, conductor 188, through thepole-changing relay 86, conductor 128 to the vertical line shaft wiper39, vertical trunk conductor 118, side switch wiper 124, Contact point145, shaft wiper 71, conductor 141, rei-tical line relay 74, winding 146of the differential relay 88 to the battery lead 126. thence throughbattery B and to ground G. The relay 86. upon energizing, operates todisengage the springs 121V and 122 and. springs 182 and 188, and toshift the spring 108` out of Contact with the spring 104 which latter isconnected with the battery lead 94) into engagement with the spring 189which is in turn connected to ground. This operation of the relay 36closes a cirruit which provides the calling subscriber with batterycurrent for talking purposes. The/'said circuit extends from ground G3through the side switch wiper 45, Contact point 118,` conductor 190,springsV 189- and 103, through the winding 106 of the differential relay63, rotary line relay49, conductor 105, rotary line conductor 91,primary winding 5, transmitter 7, springs 26 and 25, vertical lineconductor 90, conductor 92, vertical line relay 47, winding 93 of thedifferential relay 63'to theJ battery lead 94, thence through batteryr Band tov ground Gr. The two substations being thus provided with batterycurrent for talking purposes,

communication may now be carried on overl thecircuit shown `by the heavylines in Figs. 1 and 2. n l

The release ofthe 'switching apparatus is brought about when the callingsubscriber restores the receiver 2 tothe switch-hool 3, thereby pressingthe release springs 32, 33 and 34 into engagement for a moment. TheContact ofthe said release springs grounds the vertical andl rotary lineconductors 90 and 91 simultaneously from ground G" to thereleasespr1ng32, thence through the n springs 33 and 34 to the rotaryand vertical line conductors. The grounding of' the roi tary lineconductor 91produces a short-circuiting or shunting of the rotary linerelay 49 in series withthe winding 106of the dif'- ferentiall relay 63,extending from ground G3 to theoside switch wipe-r 45, contact point118,1springs 189and 103, winding-106 of the differentialrelay 63, rotaryline relay 49 tol the rotary line conductor 91, to therelease springs33and 32 to groundG". Therefore, since the winding 93 of thedifferential relay 63, alone 'carries current, the said relay be comesenergized and attract-s its armature,

'which shifts thespring 187 out of contact with the spring 186', andplaces the springs ,191' and `192 in engagement. The disengagement ofthe springs 186 and 187 destroys the energizing circuit through therelay 36, and the-spring 103 passes out ofengagement with the spring 189rand into contact with the spring104, which removes the saidshortcircuit froin the rotary relay 49 andvvind- `ing 106, establishingan venergizing circuit instead extending from xthe` substation groundG"through the release springs 32 and33 to the rotary line conductor91,relay 49, winding 106 of the differential relay 63',"

tln'ough thesprings 103 and 104 tothe batter); lead 94,'thence throughbattery ll and to ground G. The rotary relay 49 now operates and thesprngs 193 and 194 come into Contact, whereby an energizing'eirouit isestablished through the releasemagnet 51 of the selector (l. inpassingthrough the winding 106, as above stated', aids the winding 93 inmaintaining the springs 191 and 192 in Contact. The

energizing circuit through the; release mag-- net51 extends from ground@2te the springs 193 and 194;! release magnet 51, springs 191` and 192to the battery lead 94, and through However, the current `now battery toground G. rllhe release magnet energizes and remains in readiness torelease cuit is broken. Both the vertical and rotary line relays47` and49 being energized simultaneously, the trunk line conductors 113 and 114leading to the sub-central station become grounded simultaneously overcircuits previously pointed out. The grounding of the rotary trunkconductor 114 produces a short-circuit of the rotary line relay 7 5 `inseries with theI winding 153 yof the differental relay 88 .extendingkfrom ground Gr7 tof the contact point 161", side switch Wiper 85',springs 186 and 154, winding 153`of the -differential relay 88, rotaryline relay to` the rotarytrunk conductor 142, shaft wiper 72, Wiper 135,rotary trunk` conductor 114l and to ground G2. Therefore, since thewinding 146 of the differential relay 88 alone carries current the saidrelay becomes energized and attractsits armature, which shifts thespring 165 out of contact with the spring 185 and,l into contact withthe spring 164.

The `disengagement of thel springs 165 and 185 destroys the energizingcircuit through the relay 89, and the spring 154 passes out ofengagement with the spring 186 and into contact with the spring 155,which removes the said short-circuit from the rotary relay 75 andwinding 153, and establishes an enerwizing circuit instead extendingfrom ground 2 at the selector C to the battery lead 126' and then toground G', as explained. The

` rotary relay 75 now operates and the springs 195 and 196, releasemagnet 87, springs 164 y and 165 to the battery lead 126, thencethroughbattery B and to ground G. Vhen the connector release magnet 87 is thussupplied with current it 'energizcs, and

' the selector switch when the energizing cirsofi as a result theswitch-shaft and side switch y l are restoredfto normal positiointhusbre-ak,- inggthe connection between the connector `switch-,shaft wipers76; 77fand" 78 .and the normal cond'uctors158, 159 and 160. Theback-release relay 69- of the selector F being in the sameecircuit withthe release magnet cnergizes simultaneously with the'latter, andopera-tes to closea circuit through the selector release magnet 68 bypressing; the backrelease springs 198' and'199together, The circuitthrough the saidV release'magnet 68- stored.

extends troni ground Gl through the springs 198 and 199 to the releasemagnet (55, therme to the battery lead 126 and through battery lltoground G. W hen the ground to the line conductors 90 and 91 isinterrupted all the magnets involved in the release are deenergized andall the switches are fully re- 1t.v will be understood, of course, thatwhen the connector switch l) is released and the wipers 76v and 77disenga-ge from the normal conductors 158 and 159.,.the backbridge relay89 oi'f the connector D is re-,

stored and the spring 15d-,controlled by said relay returns into normalengagement with the non-grounded battery spring 155, thus cutting orftalking battery/,current iirorn the calling line. Il: the called`lineplt2209. is busy at the t'rne that the calling subscriber .#5000attemptsto establish connection, the

f connector D `is released by the last impulse to the rotary trunkconductor 11d as itollows: 'l'he said' impulse energizes the rotary linerelay 750i? the connector l), which relav in turn energizes the privatemagnet 82, pie-ssing the private springs 299 aml2G1 into contact afterthe private wiper 78 has been carried onto the grounded privatevbanlrcontact. Of course, itis understood that whenever a line is busy theconnector private bank contacts connected with the private normal 160,shown at theselector E, are all connected to ground. Therefore, sincethe connector side switch is in second position, when the privatesprings 290 and` 201 are brought into contact an energizing circuit isestablished through the releasemagnet 87 irorn the said grounded privatebank contact to the private wiper 78',.thence to the side swtch `wiper85 (which is in second position), to the private magnet springs 200 and201, to the release magnet-87, springs 16% and 165 to the ,battery lead126, thence to batteryli and to ground GC The connector s itch-shalt andside switch are thus released in tlie manner disclosed in the said`connector patent, and connection is not es` tablished wth the calledline, Anor is there anyliabi'lity of the back-bridge relay 89energizing, thus makingv it impossibleI for the calling line to receivetalkingbattery current. The busy signa-l is established whenthesul'izuariber presses his signaling button 2b, aliter he hascompleted the calling oper ations. and,ot course, after the connector isreleased, as described. The connector side switch being in firstposition, as explained, when the vertical lineconductor is grounded bypressing the signaling 'button spring 29 onto the ground contact 31, theconnector.'

vertical line relay 74C 'is then 'energized as before. Therefore, theline relay springs 14-7 and 148 are brought into contact, and thevertical magnet 79 is operated to raise the switch-shaft, whereby theott-normal springs 202 and 208 are brought int-o contact and a busysignaling currentis sont to the callingsubstaton Yfrom the busy coil lthrough the springs 203 and 292 to the side switch wiper 841,ringerrelay springs 166 and 167, condenser 218 to the rotary trunkconductor v114, Condenser 61 of the switch C to the vertical lineconductor 90, thence through the primary winding 5 to the rotary lineconductor 91, and through the condenser 62 oi' the switch C tov thevertical trunk conductor 113, line relay 74 of the connector l), andwinding 146 of the .differential relay 88 to thefbattery lead 126, andto the busy coil l, When the subscriber hangs up his receiver afterreceiving the busy signal, he grounds the line conductors 90 and 91simultaneously, energizing the line relays of thev selector' C andconnector' D simultaneously, asalready explained, thus producing thereleasey of the y switching apparatus as liollo'ws i Y As soon as thevertical and rotary line conductors 90 and 91 are ground-ed, thevertical and rotary line relays l? and 19 and the differential relay 68ot the switch C are energized,v whereby the line relay springs 193 and194C are brought into Contact at the same time that the differentialrelay springs 191 and 192 are brought into contact; thus an energizingcircuit is established through the release magnet 51 over circuits thathave already been pointed out. At the same time the line relay springs96 and 107 are, or" course, carried onto the ground spring 95, and as aresult the trunk conductors 113 and 1.14 are grounded simultaneously,whereby the vertical and rotary line relays 74 and 75 and thedifferential relay 88 are energized simultaneously, causing the releasemagnet 82 of the connector D and the.,

back-release relay 69 of the switch F to be energized simultaneously.AAs a result of the energizing oi the said release magnet the connectoris released, as already eX- plained; buty the remaining` releasecircuits and rmechanisms are retained in readiness to perform the `linalreleaseoperations as soon as the ground circuits are removed from theline conductors, at which time a release of' all switches follows in theinanner already explained. The selector C, in addition to establishingconnectionv in a distant sub-central` may also be used` in establishingconnections iu the local central ollice; thatv the subscriber atsubstationl A may call other subscribers whose telephone lines terminateinthe saine olice. ln that event the shaft wipers 89, l0 and l1 areraised and rotated into engagement with contacts of those bank levels inwhich conductors lead to selector switches located in the sarne ollice,one of which 'is diagrammatically shown at N in Fig. 1. I do not conine.niv improved selector switch (C to the exact location in a central oiceshown in Figs. l and 2; for as shown in l? ig. 3 the callingy substationi is ma. have. alloted thereto a selector switch d of the type disclosedin said selectorv patent, and the selector C may beemployed as thesecond switch on the line from which the impulses delivered totheselector switch C are repeated (as explained) to the next switch,which latter may be in a distant subfcentral exchange, ormay bein thesame local office as ktheselector C. lt will be understood that when theselector switchC is used in this manner the normal conductors 204, 205and 206, shown in Fig. l, leading to the yselector C then lead `to theselector J, Fig. 3, since the latter is allotted to the line l#5000, andthe selectors C are employed on a percentage basis-that is, to a groupof one hundred first selectors there may be allotted a group of tenselector switches C; and, also, they trunk-release spring 193 which wasformerly connected to ground then leads to the private wiper bank of theswitch J and to other vbanks in multiple. As shown in Fig. 3, theselector switch {lcoinprises the vertical and rot-ary line relays 207and 208 which receive battery 'current through the springs of thebridge-'cutoff relay 209. The said line relays are `adapted to operatethe Vertical magnet 210, privatel magnet 211, and both relays acting'conjointly provide means whereby the calling subscriber may energize therelease magnety 212 while the side switch wipers are in firstor secondposition. Asis well lrnown, the rotary magnet 213 imparts to `the shaftwipers 214, Lliand 216 their rotary or circular motion. The releaserelay 217 provides means whereby the selector may be released afterconnection has been established by `way of the shaft wipers ,214 and 215with the next Y switch. As shown in said Fig'. 3, the selector J has`established connection with the selector C,iand the selector Chas inturn seized al trunk line which may lead to another central yotlice.Furthermore, the selector switch .may be operated to engage trunk lineswhich lead to other selector switches N, said selector switches beingsimilar to the selectors F or C. Similarly7 the switch C is not connedtothe function of establishing distant trunking connections, but isadapted to perform the usual functions of selectorswitches. It will benoticed by comparing); selector J with selector F that anothermodification or special yfeature in the said switch F consists in theprovision of two line relay release springs 219 and 220, so that if itbecomes necessary to release a connection before the side switch of thesaid switch Fpasses to third position the release magnet 68 will beenergized `directly by the operating of the linerelays (Stand 65, whichrelays upon thus operating press the said springs 219 thereof.l

and 220 into Contact, establishing a circuit` throughl` the releasemagnet 68 ,from ground i5 through the saidsprings` 219,*` and 220, andthrough the releasemagnet to battery.

The various `rela-ys may be ofany ,suitable resistance, but goed results"have been obtained when the vertical and rotary line relays 4,7 and4:9, are wound tok aresistance of five hundred ohr-os each; the relayv36 to a resistance ot tive hundred ohmsg'end the windings ot thedifferential. relay 63 .to a resistance of two hundred and fifty ohmseach. A o

ln either embodiment of my. invention therefore, as shown in Figs. l and`3, proing' talkin current from the battery or other centralized sourceto the callingisubscribers line to charge the microphone transmitter ltwill be seen,` of course, that these. relays also have more or less todowith they releasing` of thein allotted selector mechanism, in the mannerexplained. With such arrangement a pole-changing relay is provided forthe calling subscriber, pas, for

example, in a combined iselector and repeater, and another pole-changingVrelay is provided forgthe called subscriber,.as, for example'7 in thecommon battery connectorf. The current for chargingthecallingsubscribers microphone transmitter is received through theline relays of a selector switch,

while the current for charging the kcalled subscribei"s microphonetransmitter is received through the windings of a connector relay. Thusthe combined selector and repeater C is adapted for the double functionof selectively trunking and repeatingin one and the same direction` andis adaptedfor controlling' yand regulatingv the 'flow of talkingcurrentto the calling subscriber7 regardless of whether it is employed `intheposition `shown in. l, or in the manner shown in Fig. 3. In either case.ras erh plainechit will be seen that the calledy subscriber controls theoperations by which the battery. is switched into the `bridge betweenlthe two line relays of the said selector and repeater C to supplytalkingn current tothe calling subscriberA The trunk-selecting andimpulse-repeating :functions of ,the switching' machine Care however,controlledby the calling subscriber before the called subleoanyiautomatic switch mechanism for connecting with the other end of saidtrunk line, aline relay allotted to and controlling said mechanism,another line relay allotted to and controlling the said automaticswitch, a circuit by which the first relay controls the second relayover the trunk line, a circuit for energizing the first relay to causethe said switch mechanism and automatic switch to be controlledrsuccessively thereby, a mo- Jcor magnet for said mechanism, a circuitfor said magnet extending through contacts of said first relay, andmeans for operating said automatic switches by a varying number ofimpulses.

2. In a telephone exchange system, the combination of a callingtelephone line, an automatic switch, an idle trunk line leading to saidswitch, a selector switch mechanism for extending connection from thecalling telephone line to the said idle trunk line, a pair of linerelays for controlling said selector switch mechanism and adapted tocontrol the operations thereof, means by which the calling subscriberalso employs said relays for controlling the operations of the saidautomatic switch, means for feeding talking current through the windingsof said relays to the calling subscribers substation, a motor magnet forsaid mechanism, and a circuit fo-r said magnet extending throughcontacts of one of said relays.

`3. In a telephone exchange system, the combination of an idle trunkline, an automatic selector switch mechanism for making connection withsaid trunk line, a pair of line relays for controlling` said selectorswitch mechanism, an automatic switch responsive to said relays andforming the terminal of the other end of said idle trunk line, means forcausing said pair of relays tio successively control the said switchmechanism and automatic switch, means for feeding talking currentthrough the; windings of said relays to the calling subscriberssubstation, a motor magnet for said mechanism, and a circuit for saidymagnet extending through contacts of one of said relays.

4. In a telephone exchange system, the combination of trunk lines, anautomatic trunk-selecting switch for extending connection over any oneof said trunk lines, a pair of relays for controlling saidtrunksele-cting switch, an automatic switch at the ofl'lher end of eachtrunk line, each automatic switch being responsive to said relays afterconnection is made with the trunk line allotted to such switch, acalling subscribers impulse-transmitting device by which said relays arecaused to successively control the said trunk-selecting switch and anidle one of said automatic switches, means for feeding talking currentthrough the windings of said relays to the calling subscriberssubstation.y a motor magnet for said first switch Vand a circuit forsaid magnet extending telephone line, and suitable instrumentali-` tiesfor supplying talking current through the windings of said relays to thecalling Subscribers line, and through the said automatic switch to thecalled subscribers line.

6. An automatic selector switch provided with a pair of line wipers, apair of crossed or transposed line conductors permanently connected tosaid wipers, means including a relay for causing a step-by-stepoperation of said wipers; trunk line terminals adapted to be engaged bysaid wipers, automatic means for preventing the wipers from engaging theterminals of busy trunks, magnets by which a subscriber operates thesaid switch, circuits for said magnets independent of said lineconductors, and switches at the end of said trunk Vlines adapted to becontrolled by the said first relay.

7. The combination of a line, a plurality of trunks, a trunk selector inwhich Asaid line terminates, automatic switches in which the said trunksterminate, a pair of line relays associated with the said trunkselector` and adapted to control the trunk-selecting operations thereof,and means by which said relays are caused to repeat switch-operatingimpulses from said line to an idle trunk after a selection of the latteris made, a motor magnet for said trunk selector, and a circuit for saidmagnet independent of said line and trunk extending through contacts ofone of said relays.

8. The combination of a subscribers line, a suitable trunk, switchingmeans individual to said line for connecting with said trunk, a secondswitching means responsive to said first switching means and located atthe end of said trunk, means for using said first switching means tooperate the second switching means after the line and the trunk arejoined together, means in said switching means to supply current fortalking purposes, motor magnet for said first switching means, and acircuit for said magnet directly controlled by said last means.

9. ln a telephone exchange system, the combination of a callingtelephone line, a called telephone line, means including a selectorswitch and a connector switch for joining the two lines together, a pairof line relays for the selector for Vcontrolling` the operation of saidselector to extend a connection, a pair of resistance windings for theconnector, two common batteries or centralized sources of'currentsupply, means for switching one battery in series betweentl'ic twowindings yof thev selector relays toy sup ply 'current to the callingtelephone line, and means for including the` other battery in seriesbetweenthe resistance windings ot' the connector to supply talkingcurrent to the called telephone line.

10. inria telephone exchange system, a pair of condensers, a line havingthe two sides thereof terminating in said condensers, a pair of linewipers, trunk line terminals tor said wipers, a pairoifcrossedconductorsv connecting saidI condensers with said linev ywipers, a pair`of relaysbridged across the line relays, a trunk line having a terminaltemporarily engaged by said line wipers, means operated by` theenergizing or said pole-changing relay'tor switching the battery inseriesbetween the two line relays, and means 'or'supplying current overthe said trunk liney and through the said wipers to energize saidpole-changing relay.

12. In 'a telephone exchange system, the combination of a selectorprovided with a pair of line wipers and a pair of line con ductorssuitably connected therewith, a polechanging relay bridged across thesaid line wipers, a `pair of line relays bridged across the said lineconductors, a battery having one pole `normally connected between saidline relays, a trunk line `having a terminal tem porarilyengagedby saidline wipers, means,l

operated by the energizing ot said polechanging relay for switching thebattery in series between-the two line relays, means for supplyingcurrent over the saidtrunlr line and through the said wipers to energizesaid pole-changing relay, and means by which a `called subscribercontrols thefenei'gizing ot said pole-changing relay.

12%. 'An automatic selector switch compris-v ing a pair of line wipers,a pole-changing relay bridged across the said line wipers, a

iair oi' lineconductors suitablyconnected l .f

with' said line wipers, a pair ot line relays bridged across said lineconductors, abattery having one polenormally connected between said'linerelays, a differential relay havingl two windings'each of which isconnected in serieswith one of the line-rel`ays, an energizing circuitfor the pole-changing relay `controlled `bysaid diderent era-ted by theencrgizin ing relay tor switching the, in series betweenthe-.windings-ot the differential relay and the line relays, atrunlrline temporarily seized by saidV line wipers, a'source ofei'iei'gizing current, and means 'for connecting said source oi? currentwith the other end ot' said trunk line to supply current backy throughthe said wipers and through the winding of the pcie-changing relay tooperatively energize the latter. e

f '14. in a `telephone exchange system, the combination ot' a' caliingtelephoneuline. a called telephone line, a `selector switch iicyidedwith crossed or transposed line c ductors, a connector switch by whicht= "called telephoneiine is temporarily seized,

suitable trunk line connection between the two switches, relay means inthe selector for controlling its own operations as well as i the'operations ott tl e connector switch, `and suitable instrumentalities orsupply: talking 'current through the said relay. mea oi.' the selectorswitch to the"callingtele` phone line, and through the coiniector switch.to the called telephone line.

15. ln a telephone system, subscriber-s line, a plurality of trunklines, a selector switch individual to said subscribei"sy line forselecting an idle one oi'said trunlr lines, and means in said.selectorswitch for repeating impulses over said trunks.

16. In a telephone system, al pilurality oit subscribers lines, aconnector switch for connecting with a called line, a switch in`dividual to said called line, and a pole` changing relay' in saidindii'iidual switch yadapted to be energized when said connectorconnects with the called line.

17. ln a telephone system, subscribeiAv line, an automatic switchindividual thto, a' pair ot line relays bridged across line forcontrolling the operation `oit` switch, land a differential relay havingwinding connected in series with eachu of said linerelays torcontrolling the release oiI said switch.

18. In a telephone system, a calling and a `called subscribers line.means including a selector switch operative in `accordance. withthefiirst digit ol the called numb i foi-'Tex` tending the connection`trom acalling to called line, a pair ot line relays tor said selector,a pole-changing relay for said relector, and ineansiior energizing saidrelay when the called subscriber answers for profl vidiiig talkingcurrent to the calling suh.

soribers line through said line relays.

19. In a telephone system, a'pluralityot subscribers lines,y means'including a' selec tor switch allotted to each of said lines operativein accordance with the 'first `digit o't thecalled number inestablishing stalki... circuit betweena calling and a called subilo Cil

1, ribei.; relays in each or said switches 'for pplying talking currentto the talking ci rcuit, a motor magnet tor each oit said switches, anda circuit tor each or said mag nets extending throughcontacts or one ofthe `associated relays.y l v 20. ln a telephone system, a plurality oisubscribers lines, means including iirst rselectors and second selectorsfor establishing a talking circuit between a calling and a called. line,relays tor controlling; said second selector, means for supplyingtalking current to sait hing circuit-through said relays, a motor magnetfor said second selector, and circuit 'for said magnet entend-y ingthrough contactsv of one oi said relays.

21. ln a telephone system, a calling and called line, an automaticconnector switch for connecting with a called line, a plurality oi.lswitchesr tor extending' connection from calling line to said connectorto thereby establish a talking circuit between a calling and a calledline, relays for controlling one of said switches, means for supplyingtalking current to said talking circuit through said relays, a motormagnet for said switch,

and a circuit for said magnet extendingl through contacts' of one ofsaid relays.

22. ln a telephone system, a plurality of subscribers lines, meansincluding a` selector switch having line relays operative in aca x v Ecordance With theiirst digit oi the called number for establishing atalking connection between a calling and a called line, and

, means for supplying talking current to the line through said relayswhen the called subscriber answers.

23. ln telephone system` a subscribers line, a combined selector andrepeater provided with a ver ical line relay connected to battery at oneside and permanently con nected direct to the subscribers line at theother side, a rotary line relay connected to Vbattery at one side and tothe subscribers Y hist-selector and repeater provided with progressivelymovable step-by-step side switch` Wipers and line relay springs, saidWipers permanently connected directly to the line relay springs,respectively, and switching means responsive tothe same when used as arepeater.

25.' In a .telephonefsystein in which thev subscribers are divided intogroups, means having one motion to select groups and an other motion toconnect With the called lineV found in the selected group, a combinedrst-selector and: repeater providedA With Vprogressively movablestep-bystep side,

switch wipers permanently connected dir .1y to the line relay springs,respectively', and switching means responsive to the saine when used asa repeater.r

' 26. ln a telephone system in `ahicl'i the subscribers are divided intogroups, means having one motion to select groups and an-v other motionto connect vwith the called line found inthe selected group, a combinedselector and repeater for each subscriber, other switches whereby anysubscriber may obtain connection with any other subscriber, a pair otcondensers in opposite sides othe vtalking .:ircuit, each saidcoi'nbined selector and repeater includin' apair of line shaft meansrcontrolled by said relays -for then repeating` impulses over the seizedtrunk.

28. ln an automatic telephone exchange trunliing system divided intogroups, a combinedhist-selector and repeater provided with side switchWipers, and line relay springs, said Wipers permanently connect eddirectly to the line relay springs, respectively, and switching meansresponsive to the same When used asY a repeater, said selector havingone motion to select groups and another motion to automatically selectan idle trunk in the selected group.

29. ln an automatic telephone exchange trunling system divided intogroups, a combined selector and repeater for each subscriber, otherswitches whereby any subscriber may obtain connection with any othersubscribe-r, a pair of condensers in opposite sides of the talkingcircuit, each said combined selector and repeater including a pair eliline shaft Wipers permanently connested with the subscribers linethrough said condensers, said selector having one motion to selectgroups and another motion to automatically select an idle trunk in theselected group, as set forth.

30. A telephone system, means ior establishing a talking circuit,comprising trimhr lines, an automatic trunk selector, a connector havingvertical motion to select groups and rotary motion to connect with aline in the selected group, a called subscribers `telephone line adaptedto be seized by' said connector, a calling` subscribers telephone line,a relayv individual to the calling l il() line to which,tliefselectorland connector are sucres vely responsivesaid selectorrespon` sivetosaid relay viacirciiitsexcliided'trom said talking circuit,Asaid-relay associated with `and yincluded in said selector.

3l. l'npa telephonelsysteni, a calling ytelephone line, acalledtelephone line, means including an autoii'iatic trunk selector forextending la talkingcircuit'tc thecalled telephone line, havingi.verti:al motion to select groups and rotaryniotion to connect with aline inthe 'selected group, :said selector having` a controlling relaypermanently connected `to thetalking circuit and operating magnetscontrolled over ycircuits excluding said talking circuit, `a source oitalking ciir rent, and means in said` selector responsive to thecalledvsubsciibei toi ieeding talking current to the calling line.

di, telephone system, means for establishing a talking circuitcomprising a truuk having an automatic switch at one :end thereof,lresponsive to-ealliiig iii'ipulses sent over said trunk, anda combinedtrunk sevlector and `repeater mechanism tor seizing y tliewotli'er endof said trunk, when the latter is idle, having means yior transmittingthe said kcalling impulses to operate the said automatic switch, saidmechanism comprising a. relaypermanently connected to `the (Y, circuitandoperating magnets controlled over circuits excludingsaid talkingcircuit. f

38. lira `trunl'nng system in `vvhich the talkin@ Avtrunks are `in,groups, means for establishing a talking `circuit comprising a ,trunkline ran automatic sivitch includinot a )air ot line relays to which thesaid trunk line leads,a second pairfof ,line relays connected to saidtalking circuit,ineans associated with saidsecond relays and controlledthere 'by over circuits excluding said talking cir- `cuit forextendingconnection tolsaiid-t-runk line, elccti'oiiiagnetic,.means `iorsaid switch, i

and means by whichl a calling subscriber con'- ti'ols the energizingofsaid electromagnetic means through the medium ot said second relays,said switch having vertical motion f toselect groups and rotary motionto conneet withlthe, desired line in any predeter mined group.

34.1n a trunking system in` which the trunks are in groups, inea-ns forestablishing motion toautomaticallyselect anidle trunk in anypredetermined group. i

3 5. ,A te-lephOneeSyStem, vmeans tor estao-` lishingaftalking circuitcomprising trunk lines, an autoiiiatictrunk selector, anwautdiiiaticsivitcli for eaclitrunk line, said trunk selector including apairoil linek relays, and

`an automatic progressively movable Step-bystep auxiliary switch toena-ble said relays to control the connector Aafter the selectoriliasbeen operated,y the relays controlling the selector over circuitsexcluding the said talkingcircuit. f j y 86. ln a telephone system,acalling telephone line, a called l'telephone line, trunk linesconimon tosaid lines, a battery, an :iin-

pulse/sender in the calling line, an auto-v matic trunk selectorforselecting anidle i one ot' said trunk lines to extend ,a talkingcircuit` toward i the called telephone line, operating'magnets for saidselector, aiiiag net controlling relaygin lsaidsselector,` circuits forcontrolling `said magnets eizcliid ing the talking circuit, va sourceo'ltalking current, 'and a progressively inovz'ible step-by-stepelectrounagnetically f controlled switch and a relay in said selectorresponsive currenttcthe calling line. i i

37. a telephone jsystemincludiiig a call` ing" telephone line,`directive switching means at the substation thereof, 'a directivelycontrolled rstep-by-step seleetor'connected with said line,operatingrelays Vfor i said selector responsiveto said means, drivingmagnets for Aadjusting said selector' responsive to said*` relays, trunkcircuit including a pairoi' individual trunk conductorsioiily,multiplecontacts vat one endot `said circuitl at said selector and selectablethereby when said circuit is idle, .trunk relays connected Wit-h saidconductorsat-the other end of said circuit, armature switch niechanismol" therela-ys of` said selector conductivelyfcon'nected `with ysaidlast-mentioned relays on selection made ot ysaid circuit, wherebythefrelays of said selector, operating' responsive to saidsubstationvineans,

vto the called `subscriber "for feeding talking f,

directly control said trunk relays, and a ,i i

trunk selector for said circuit at said other end having operatingelectromagnets rcontrollable by said trunk relays.

38. A telephone system including a calling telephone line, directiveswitching means at the substation thereof, a selectorconnected With saidline` operating relays for said se lector responsive to said means,magnets for adjusting said selector responsive to said relays, a trunkcircuit including a pair of individual trunk conductors only, multiplecontacts at one end of said circuit at said selector and selectablethereby when said cirf cuit is idle, trunk relays connected With saidconductors at theiother end of said circuit, armature switch mechanismof the relays of the substation thereof, a selector connectedy with saidline, operating relays for said selector responsive to said means,magnets tor adjusting vsaid selector responsive to said v'relays, atrunk circuit including a pair oit individual trunk conductors only,multiple contacts at one end of said circuit atsaid selector andselectable thereby when said circuit is idle, trunk relays connectedwith said conductors at the other end of said circuit, armature switchmechanism oit the relays or" said selector conductively connected withsaid last-mentioned relays on selection made of said circuit, wherebythe relays of said selector, operating responsive to said substationmeans', directly control said trunk relays, a vtrunlr selector for saidcircuit at said other end having operating electromagnets tcontrollable.by said trunk relays, means for simultaneously energizing said trunkrelays responsive to current impulses transmitted over said conductorsby said selectorl relays when disconnection is desired, and a release`circuit of said trunkl selector operated responsivev to thesimultaneous energization of said trunk relays. 40. A telephone systemincluding a calling line, a directively controlled step-by-stepselector` at the exchange having operating relays connected with, andresponsive to directive currents over said line, travelingcoritact-makers for said selector, a link-circuit havingtwo individualconductors only Jfor conductive connection to the contact-makers of saidselector, said conductors being selectable by said selector responsiveto said relays, link-circuit relays conductively connected with saidconductors and operable responsive to currents transmitted by saidoperating relays on selection made, a selective switch for saidlink-circuit having driving magnets connected with armature switches ofsaid link-circuit relays and operable thereby, and a release circuit forsaid switch responsive to' current changes produced at said selector insaid individual conductors to release said selective switch whendisconnection is desired.

41. In telephony, a trunk circuit for automatic telephone systemsincluding a pair oi trunk conductors only, multiple terminals of saidconductors, a. directively controlled stepby-step'selector at a iirstexchange for selecting said terminals, driving magnets for said selectorand operating relays 'for controlling the same, trunk relays for saidtrunk circuit at an exchange at the distant end of said conductors,arma-ture switches ofsaid `operating relays conductively connected tosaid trunk relays when said selector selects said teiniinalswhereby saidtrunk relays are.

rendered directly controllable by said operating relays, a selectiveswitch operable by said trunk relays,-and means for restoring saidswitch responsive to circuit changes produced in said trunk conductorsat said selector. f

Signed by me at Chicago, Cook County, Illinois, this 11th day ofJanuary, 1907.

TALBOT e. MARTIN.

lVitnesses: f A

EDWARD D. FALns, ARTHUR B. SPERRY.

